Sailing Stones: The Mystery of Moving Rocks

Imagine walking across a vast, dry lake bed and discovering long trails behind large rocks—as if they had been dragged across the desert floor. Yet there are no footprints, no tire tracks, nothing to suggest human intervention. 

This is the puzzling phenomenon of sailing stones, where rocks weighing up to several hundred pounds appear to move on their own, leaving mysterious tracks across the desert landscape. For decades, these “moving rocks” baffled scientists and visitors alike, becoming one of nature’s most enduring mysteries.

What Are Sailing Stones?

Sailing stones leave mysterious trails across the dry lake bed of Racetrack Playa in Death Valley National Park.

Sailing stones, or sliding rocks, are a geological phenomenon where rocks move and create long tracks on a smooth valley floor without any human or animal help. 

Rocks can vary from small pebbles to large boulders weighing up to 700 pounds, yet they slide across the desert floor, leaving trails that can extend for hundreds of feet.

The most famous location to observe this phenomenon is at Racetrack Playa in Death Valley National Park, California. The flat dry lake bed, surrounded by mountains, provides ideal conditions for the movement and preservation of stones. 

The playa surface consists of dried mud that cracks into perfect polygonal shapes during dry periods, creating a stunning backdrop for the mysterious moving stones.

A History of Discovery and Speculation

The first documented account of the sailing stones dates back to 1915 when a prospector named Joseph Crook visited Racetrack Playa. 

However, scientific interest truly began in the 1940s when geologists Jim McAllister and Allen Agnew published the earliest formal report about the sliding rocks in a Geological Society of America Bulletin.

Scientists in the 1950s attempting to solve the mystery of the sailing stones.

For decades, scientists proposed various theories to explain this strange phenomenon. Some suggest that during rare rainstorms, when the playa surface turned slick, powerful winds propelled the rocks. 

Others hypothesized that the rocks were moved by thick sheets of ice or even magnetic forces within the Earth. More fanciful explanations involved everything from supernatural forces to extraterrestrial intervention.

In 1952, a National Park Service Ranger named Louis G. Kirk made detailed observations of the furrow length, width, and general course of the rock trails. This sparked more serious scientific investigation, though a definitive explanation remained elusive for decades.

Scientific Studies and Experiments

In 1968, geologists Bob Sharp and Dwight Carey began a systematic study of the sailing stones. They labeled 30 stones with fresh tracks and used stakes to mark their positions, monitoring them over a seven-year period. Each stone was given a name, and changes in their positions were carefully recorded.

A sailing stone with its distinctive track across the playa surface.

Their research yielded fascinating results. Ten of the initial 30 stones moved in the first winter, with one stone named “Mary Ann” covering the longest distance at 212 feet. 

The smallest monitored stone, “Nancy,” moved the longest cumulative distance—860 feet—and the greatest single winter movement of 659 feet. The largest stone to move during their study weighed about 80 pounds.

To test the ice floe hypothesis, Sharp and Carey built a corral around one stone using metal rebar. If ice was responsible for moving the stones, the rebar should have impeded its progress. Surprisingly, the stone moved 28 feet to the northwest, barely missing the rebar—suggesting that if ice played a role, it must form in small collars around the stones rather than in large sheets.

In the 1990s, Professor John Reid led research students from Hampshire College and the University of Massachusetts Amherst in a follow-up study. They found evidence supporting the theory that ice floes up to half a mile wide might be responsible for moving the stones. 

Physical evidence included swaths of lineated areas that could only have been created by moving thin sheets of ice.

The Mystery Finally Solved

The rare winter conditions that create thin ice sheets on Racetrack Playa, enabling stone movement.

After decades of speculation, the definitive solution to the sailing stones mystery came in August 2014. Cousins Richard D. Norris and James M. Norris, with their research team, published their findings in PLOS ONE after capturing the first images of moving stones.

In 2011, researchers set up a weather station near Racetrack Playa and placed 15 stones with GPS tracking units on the playa. Then, they waited. 

On December 4 and December 20, 2013, their patience was rewarded when they captured on camera rocks sliding across the playa at up to 15 feet per minute.

Nature’s puzzle was finally solved: the stones move when a rare combination of conditions occurs. First, the playa must be covered with water, just deep enough to allow the formation of floating ice when temperatures drop at night. When morning comes and temperatures rise, the thin ice sheet—only 3 to 6 millimeters thick—begins to melt and break up. 

Light winds of about 10 mph then push these large panels of floating ice against the rocks, shoving them across the slick mud surface below.

On December 20, 2013, over 60 rocks were observed moving, with some traveling up to 224 meters (735 feet) between December 2013 and January 2014 during several events. 

The researchers described it as “a perfect storm” of conditions that occurs only every few years.

As Richard Norris noted, “Science sometimes has an element of luck. We expected to wait five or 10 years without anything moving, but only two years into the project, we just happened to be there at the right time to see it happen in person.”

Cultural Significance and Folklore

Beyond their scientific importance, sailing stones have captured the human imagination and become part of our cultural landscape. Native American tribes from the region, including the Timbisha Shoshone who have inhabited Death Valley for centuries, incorporated the moving rocks into their oral traditions. In some stories, the rocks were believed to be animated by spirits or used as markers by supernatural beings.

The mysterious nature of the sailing stones has also made them a fixture in popular culture. They’ve been featured in numerous documentaries, including those by National Geographic and the Discovery Channel. 

The phenomenon has inspired artists, writers, and filmmakers, featuring in science fiction stories and music videos where stones represent unstoppable natural forces.

The phenomenon has inspired artists, writers, and filmmakers, appearing in everything from science fiction stories to music videos that use the stones as metaphors for unstoppable natural forces.

Visitors to Death Valley National Park often make the difficult journey to Racetrack Playa to witness the sailing stones phenomenon.

The sailing stones have become a symbol of Death Valley National Park, drawing thousands of visitors each year who make the difficult journey over rough, unpaved roads to witness this natural wonder. 

The National Park Service has worked to protect this fragile environment, establishing guidelines for visitors to ensure the preservation of both the stones and their tracks.

Unfortunately, the site has occasionally suffered from vandalism. In 2013, park officials investigated the theft of several rocks from the playa, and in 2016, someone illegally drove across the playa, leaving tire tracks that damaged the surface. A team of volunteers later cleaned the tracks using gardening tools and 750 gallons of water. 

These incidents highlight the importance of responsible tourism and conservation efforts to protect this unique natural phenomenon.

Similar Phenomena Around the World

While Death Valley’s Racetrack Playa hosts the most famous sailing stones, similar phenomena have been observed in other locations. Little Bonnie Claire Playa in Nye County, Nevada, has documented instances of moving rocks. Researchers have also identified comparable stone movements at Lake Natron in Tanzania, where environmental conditions occasionally create the perfect storm for rock movement.

These natural laboratories provide scientists with additional opportunities to study the complex interplay of geological, meteorological, and physical forces that create such unusual phenomena. 

By comparing the conditions at different sites, researchers can better understand the specific requirements for stones to “sail” across flat surfaces.

Each location has its own unique characteristics that influence how the stones move. Differences in rock composition, surface texture, wind patterns, and water chemistry all affect how stones move and create tracks. 

This diversity of conditions helps scientists refine their understanding of the fundamental processes at work.

Visiting the Sailing Stones

For those wishing to witness this natural wonder firsthand, visiting Racetrack Playa requires careful planning. The playa is in a remote part of Death Valley National Park, reachable only by a rough 27-mile unpaved road that needs a high-clearance, four-wheel-drive vehicle.

Flat tires are common, and there is no cell service, so visitors should bring spare tires, extra water, and emergency supplies.

The best time to visit is during the cooler months from October through April. Summer temperatures can exceed 120°F (49°C), making it dangerous to venture far from your vehicle. While you won’t likely see the stones actually moving (that rare event happens only every few years during specific winter conditions), you can observe the tracks and the stones in their current positions.

The challenging unpaved road that leads to Racetrack Playa requires a high-clearance, four-wheel-drive vehicle.

The National Park Service asks visitors to respect this fragile environment by staying on designated paths and never driving onto the playa surface. Walking on the playa is permitted, but visitors should tread lightly and never move the stones or create fake tracks. 

Remember that removing rocks or disturbing the playa surface is prohibited and damages this unique natural laboratory.

If you’re unable to make the journey in person, virtual tours and high-resolution photographs are available through the National Park Service website and various educational platforms, allowing everyone to experience the wonder of the sailing stones from afar.

Nature’s Enduring Mysteries

The sailing stones of Death Valley illustrate how nature can create incredible phenomena using a unique combination of everyday forces. What once seemed magical has been shown through scientific investigation to result from specific environmental conditions working together.

The mysterious beauty of sailing stones at sunset, a reminder of nature’s endless capacity to surprise and inspire.

Yet even with the mystery solved, the sailing stones continue to captivate us. They remind us that our planet has secrets to uncover and that the natural world follows principles that may seem magical until we understand the science behind them. 

Like nature’s chess pieces gliding across a desert board, these rocks demonstrate the beautiful complexity that can arise from simple natural forces.

As we contemplate the sailing stones and their meandering tracks across the desert floor, we might wonder: what other natural mysteries remain unsolved? From the precise mechanisms behind animal migration to the unexplained phenomena of ball lightning or the origins of life itself, our world continues to challenge our understanding and inspire our curiosity. 

What seemingly impossible puzzle will science solve next?